The disclosures herein relate in general to digital signal processing, and in particular to a method and system for temperature protection of a speaker.
Many portable electronic devices are relatively small and inexpensive. Accordingly: (a) such devices may have speakers that are relatively small and inexpensive; and (b) drive units of the speakers may have relatively low power handling capacity and relatively low sensitivity, which increases risk that a powerful amplifier might push them to power handling and mechanical limits in an attempt to reach higher sound volumes. Causes of speaker failure include: over-excursion (e.g., excessive backward and/or forward movement) of the speaker's diaphragm; and overheating of the speaker's voice coil. For example, if the amplifier pushes the speaker to its power handling limit, then the speaker's temperature is more likely to increase until resin on the speaker's voice coil melts (thereby causing short circuits) and/or flux of the speaker's magnet structure is damaged (thereby causing loss of sensitivity and control).
In one example of a conventional technique for temperature protection of the speaker: (a) a sensor monitors temperature of the speaker's voice coil; and (b) if the sensor indicates that temperature of the speaker's voice coil exceeds a threshold, then the amplifier's gain is reduced across an entire band of the speaker's received input voltage signal. A shortcoming of this conventional technique is that perceived loudness to a human from the speaker is significantly reduced. Accordingly, a different technique would be useful for temperature protection of the speaker.